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Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates
Published on: January 17, 2018
Donor-acceptor random regioregular π-conjugated copolymers based on poly(3-hexylthiophene) with unsymmetrical
Kaoru Uegaki1, Kazuhiro Nakabayashi2, Shin-Ichi Yamamoto1
1Department of Applied Chemistry, National Defence Academy 1-10-20 Hashirimizu Yokosuka Kanagawa 239-8686 Japan.
Abstract:
Donor-acceptor π-conjugated random copolymers based on regioregular poly(3-hexylthiophene), rr-P3HT, with unsymmetrical monothienoisoindigo moieties were obtained by direct arylation polycondensation of 2-bromo-3-hexylthiophene with unsymmetrical monothienoisoindigo motifs under the optimized conditions [palladium-immobilized on thiol-modified silica gel with chloride counter anions, PITS-Cl (2.5 mol%), PivOH (1.0 equiv.), K2CO3 (3.0 equiv.), DMAc, 100 °C, 24 h]. Incorporation of unsymmetrical monothienoisoindigo electron-acceptor units into the polymers tuned their highest occupied and lowest unoccupied molecular orbital levels, which were close to those of the hole transport material (PEDOT) and electron transport material (PCBM), respectively, in thin-film organic solar cells. Alkyl chains of the unsymmetrical monothienoisoindigo units in the polymers tuned their macrostructural order, resulting in the observation of crystalline patterns and specific absorption peaks in thin films. An organic solar cell containing the most crystalline random copolymer showed an efficiency of 1.91%.
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